The Interaction of Background Internal Waves and Wake over the Horizontally Moving Sphere in Stratified Fluids

Abstract

The results of experimental studies of the interaction of background internal waves and processes, caused by the movement of the sphere in a stratified fluid are presented in this paper. Two distinct types of stratification are considered: a profile with a distribution of density that is close to linear and profile with a distribution of density that contains the pycnocline of finite thickness. The contact methods and schlieren-method are used in this study. Statistical processing of experimental data, including digital analysis of the shadow images of fluid and spectral analysis, are performed. It is shown that the presence of background internal waves leads to the transform of a wake over the sphere. The presence of background internal waves indicates more intense vortex transfer in the fluid due to the interaction of vortex motions from two different sources. Pycnocline prevents the propagation of perturbations from a moving sphere to the free surface. It is shown that the processes of interaction of background internal waves and a wake over the sphere in a stratified fluid play an important role in a formation of turbulent and wave motions in a stratified fluid, the type of a density stratification is of major importance.